The present invention relates to an optical apparatus, such as an image pickup apparatus and an interchangeable lens.
The conventional optical apparatus, such as a digital camera, moves a focus lens to a focused position in accordance with a distance measuring or focus detecting result, and takes a picture using an image pickup device after the imaging optical system is in a focused state.
Any impacts upon the camera after the imaging optical system is set to a focused state may possibly reposition the focus lens and cause defocusing. The above impacts may possibly shift positions of one or more lenses in the imaging or viewfinder optical system, and may possibly change a shooting angle of view and a viewfinder's angle of view.
In a conventional digital still camera, a half-press of a release button starts the distance measurement, focusing and photometry. Whether a flash unit as a light emitting unit is to emit the light or not is determined based on the photometric result. When it is determined that the flash unit should emit the light, the flash unit accommodated in the camera is automatically popped up to a projecting position.
In general, the pop-up is so fast in a pup-up type flash unit that a mechanical impact applies to the camera during the pup-up time. Therefore, the vibration may possibly change the lens position as discussed above.